The invention relates to a laser having a stimulation path which is sub-divided into a plurality of partial paths and having a plurality of optical connecting paths connecting the partial paths to one another, possibly via deflecting mirrors.
The invention relates particularly to heavy-duty lasers for industrial applications, for example for the welding and cutting of metal. For the high level of light amplification in the laser resonator and thus the high laser output required for these purposes, long stimulation paths are required along which the laser medium is exposed to the stimulation energy of a stimulation energy source while the laser beam within the resonator is able to interact with the laser medium.
Long rectilinear stimulation paths require a generally undesirably long overall length of the laser and considerable outlay in order to provide mechanical stability.
In order to avoid long rectilinear stimulation paths, there has been a tendency to use deflector mirrors to `fold` the resonator beam, in order to sub-divide the stimulation path into a series of partial paths. These partial paths can be accommodated in a comparatively small space. In the case of the prior art fold patterns, such as the Z-fold or the U-fold where the resonator beam is folded to a Z- or a U-shape, for example in a cylindrical or rectangular body, the problem arises that the stimulation paths which act as heat sources when the laser is operating and which are sub-divided according to these fold patterns give rise to a complicated anisotropic distribution of temperature within the laser and which can in turn bring about highly anisotropic heat expansion in partial path components or carrier and housing parts. Such heat expansions which are marked in varying extents in different directions can easily lead to a self-maladjustment of the resonator beam so that the laser no longer functions reliably. This problem occurs particularly in high-output lasers in which the laser medium becomes correspondingly and intensely heated when the laser is operating.